A statement on the crash of Egyptair flight 990 in, 1999
Egypt-USA, Local, 3/23/2002

Egyptian Civil Aviation (ECAIT), a partner to the investigation into the cause of the crash of EgyptAir Flight 990 on October 31, 1999, provides the following analysis of the available evidence collected thus far during the investigation, including factual data gathered by the National Transportation Safety Board ("NTSB") working groups and the Egyptian investigation team.

Although, the ECAIT believes that the investigation is not yet complete, certain conclusions can be drawn.

1. Regarding the probable mechanical failures:

- An analysis of the facts and the elevator control system's design indicates that malfunctions in two power control actuators (PCAs) on the right elevator may have precipitated the airplane's dive.

This dual PCA malfunction may have consisted of a latent or nearly latent, failure in one PCA that may have existed for an extended period of time followed by a jam of a second PCA shortly before the dive.

An analysis of the facts and the elevator control system's design indicates that malfunction of one of the elevator body cable (Aft elevator cable break with fwd end of broken cable jammed), shows a very close consistency with the elevators FDR data during the dive, warranting further tests.

2. The facts do not support the initial, and widely reported, theory that the first officer deliberately dove the plane toward the ocean.

3. Without further information concerning the data from military and FAA radar, one cannot rule out the possibility that the first officer may have been attempting to avoid or maneuver the aircraft out of a perceived dangerous situation at the time the dive occurred.

Accident Background and Investigation Status EgyptAir Flight 990, a Boeing 767-300, bound for Cairo crashed into the Atlantic Ocean shortly after takeoff from John F. Kennedy International Airport, New York, on October 31, 1 999.

The aircraft impacted the ocean at approximately 0150 EST, 60 miles off the coast of Massachusetts. All 217 passengers and crew perished.

Shortly after being notified for the crash, NTSB Board Chairman Jim Hall contacted the Egyptian Civil Aviation Authority ("ECAA") to seek authority to conduct the investigation on behalf of the Egyptian government.

Pursuant to Annex 13 to the convention on International Civil Aviation, the Egyptian government delegated authority for the management of the investigation to the NTSB. EgyptAir was provided party status pursuant to the convention.

The ECAA and EgyptAir dispatched a number of investigators to participate in all aspects of the investigation. Since last November, these investigators have resided in Washington, D.C., gathering and analyzing the evidence.

Additional experts, including interpreters, religious authorities, metallurgists, engineers and aerodynamicists have also been called upon to assist in the investigation.

Today, additional aircraft systems tests and additional radar information are needed before the NTSB's factual investigation can be closed and the true cause of this tragic accident determined.

One thing is certain, though - the evidence gathered in this investigation does not support the conclusion that the first officer deliberately dove the aircraft into the ocean.

To the contrary, the factual evidence indicates that an elevator control malfunctions may have occurred causing the crash.

1. Evidence developed during the investigation concerning probable mechanical malfunctions:

1.1 Dual elevator PCA's valve jam on the right side:

Each elevator surface on the Boeing 767-300 is hydraulically powered by three actuators.

With dual PCA's valve jam failure on the same side, the affected elevator will move uncommanded to the maximum down position for the existing flight conditions, with no further control available from either control column.

This elevator movement will only be affected by airplane speed and attitude. The unaffected elevator will follow the affected site.

Again, no visual or aural warning the flight crew is associated with this failure. The elevator deflections described in this scenario are consistent with elevators' behavior during the accident sequence.

Only four of the six elevator actuators from flight 990 have been recovered from the ocean. One actuator, identified as that from the right elevator out board position, contained abnormalities when compared to the remaining three actuators recovered.

These abnormalities include the Following:

(a) the actuator's hydraulic piston found in a fully retracted position (airplane nose down) which is consistent with a jammed servo valve;

(b) an unusual separation of the spring guide in the servo valve commanding the piston.(Because of the orientation of the servo perpendicular the direction of flight and no accelerations required to fail the connecting pin to the spring guide, the observed damage could not have been impact related.); (c) overriding positioning of bias spring coils with respect to the spring guide; and

(d) particulates in the servo cap where the spring guide and spring coils are housed. In addition, examination of the bellcranks for this actuator and the adjacent middle actuator disclosed rivet shears that may be consistent with a jammed condition in the actuators combined with input forces to the control column trying to move the elevator to an airplane nose up position.

All the remaining bellcranks recovered were found to have rivet shears in the opposite direction. One of these was from the adjacent right elevator inboard actuator linkage position that still had continuity of the input rod to the middle bellcrank.

It is known that jamming of an actuator can occur without leaving any direct evidence of a jam. Indeed, the NTSB has so concluded in at least two accidents involving Boeing aircraft- USAir Flight 427 at Pittsburgh and United Airlines Flight 85 at Colorado Springs.

Although no direct evidence of jamming has been disclosed in the actuators examined, the circumstantial evidence indicates that such jamming may have occurred. Further, there are two remaining actuators for this accident airplane that remain unaccounted for. These actuators may reveal evidence of jamming or other unusual conditions.

Over the past five years, there have been a number of reports of bellcrank rivet shears in the Boeing 767 actuator bellcranks, which are designed to occur as a result of a jam in the elevator control system. Until recently, the linkage shears were confined to a single bellcrank actuator.

On July 20, 2000, Boeing sent a letter to all 767 customers advising them of the possibility that the elevator single system hydraulic test certified maintenance requirement may not detect a sheared bellcrank rivet and that the federal aviation administration plans to release an immediate adoptive airworthiness directive concerning this issue.

This validates the safety issues addressed by the Egyptian Civil Aviation Authority to the FAA in June 2000.

1.2 Malfunction of one of the elevator body cable (Aft elevator cable break with fwd end of broken cable jammed):

Two pairs of control cable transmit the command inputs from the Captain and First Of ficer elevator control columns at the control cabin, to the six elevator power control actuators driving the elevator surfaces (elevators deflections are dependents on the amount and direction of the input commands, aircraft speed, aircraft altitude and stabilizer position). Malfunctions of the body cables might affect the pilots commands to the elevators PCA's.

An aft elevator cable break with fwd end of broken cable jammed (at the left First Of ficer Cable) will result in the following:

Both elevators will move down (Elevators trailing edge down) Both columns move forward Inputs from the Captain side can move both elevators. Elevators will move almost equally when commanded to the Trailing Edge down direction. When commanded in the Trailing Edge up direction, the right elevator will have limited travel even at very high input forces.

Inputs from the First Officer side can move both elevators. Elevators will move almost equally when commanded to the Trailing Edge down direction. When commanded h1 the Trailing Edge up direction, both elevators will have very limited travel even at very high input forces.

Based on the limited available tests data processed by the Egyptian Investigation Team, the failure condition "Aft elevator cable break with fwd end of broken cable jammed", shows a very close consistency with the elevators FDR data during the dive warranting further tests.

2. Boeings Analysis of the Ground Tests and Flight Simulation: 2.1 Boeings Analysis of the Ground Tests and Flight Simulation concerning the validation of the dual PCA's valves jam malfunction: Boeing agrees that a dual actuator failure on one side can occur on the Boeing 767-300 aircraft. Boeing also agrees that such a failure scenario would cause the aircraft to dive downward with no warning to the pilots of the aircraft.

The analysis of the ground test results revealed that the elevator control system on the test airplane did not behave exactly as was predicted by the Boeing engineering data.

Therefore, the engineering data (that did not exactly match the behavior of an actual Boeing 767) should be very carefully used when evaluating the possibility of an elevator malfunction as being a cause for the EgyptAir 990 accident.

In particular, care must be taken when comparing the FDR elevator data with the predicted results based on this data. Lot of inconsistencies in the ground testing and Boeing analytical prediction were visible.

A thorough analysis of the E-Cab simulator testing shows that the behavior of the simulator was unlike the airplane in several key aspects (motion, g loading, interconnect between columns, etc.) that makes conclusions based on the simulator performance not accurate.

In addition, the E-Cab is designed to behave in accordance with the Boeing engineerdlg data that was shown to inaccurately represent the behavior of the Boeing 767 elevator control system during the ground tests.

In addition, the actual airplane behavior at Mach numbers above 0.91 is not included in the simulator software. Instead, the aerodynamic database is extrapolated from Mach 0.91 to 0.98. Simulation modifications were made to lift, drag, and pitching moment parameters at speeds beyond the dive Mach number of 0.91. A "small artificial 'delta Cm trim' was introduced".

The elevator column override mecllanism is not included in the simulator because there is only one control loader. Boeing's analysis only considered steady state values from Boehlg's published data to Calculate forces on the control column in various flight conditions.

2.2 Boeings Analysis of the Ground Tests and Flight Simulation concerning elevator body cables malfunction:

The objectives of these ground tests were to check the effect of introducing the following failures in Boeing 767 the elevator control system, including the followhlg: - Measuring the response of the 767 elevator control system - Measuring the elevator control available from the left and right control columns after insertion of these failure conditions

Producing factual documentation of the testing

Elevator body cable malfunctions which were included are:

Aft cable break, Aft cable jam condition at the left First Of ficer Cable

Aft cable break, Fwd cable jam condition at the left First Of ficer Cable

Fwd cable break, Aft cable jam condition at the left First Of ficer Cable Fwd cable break, Fwd cable jam condition at the left First Of ficer Cable Single PCA valve jam on the right elevator (outboard PCA) (20 % offset from valve neutral position with a modified high force Break-Out pogo (35 pounds instead of 15 pounds) Additionally and following the completion of these tests, the system group chairman, detennined that further testing was required to document the characteristics and elevator control available from each control column following a forward cable break with forward cable break with the forward section of the cable jammed. The purpose of these tests were:

a- To determine if the failure transient time could be affected by human action with the control column.

b- To determine if the elevators could be commanded to various positions that could correspond to the flight data recorder data from the accident aircraft.

The Egyptian Civil Aviation Investigation Team asked also to conduct the same tests for the case of aft cable break, forward cable jam.

In addition, the Egyptian Investigation Team asked to insert the failures with autopilot engaged to check the resulting cockpit indication and warning. These tests have not been conducted due to time constraints.

Based on the limited available tests data processed by the Egyptian Investigation Team, the failure condition "Aft elevator cable break with fwd end of broken cable jammed", shows a very close consistency with the elevators FDR data during the dive warranting further tests.

3. The Evidence Refutes the "Deliberate Act" Theory 3.A. creation of the "Deliberate Act" Theory

Within two weeks following the crash, the flight data recorder (FDR) and the cockp t voice recorder (CVR) were recovered from the ocean floor and initially analyzed by the NTSB and other federal investigators. Based primarily on an inaccurate translation of the first of ficer's use of a Muslim phrase contained on the CVR and other out of context infonnation selected from the FDR.

U.S. government sources "close to this investigation" theorized that the first officer Gameel El Batouty dove the aircraft into the ocean. Now that the CVR has been accurately translated and the FDR has been thoroughly analyzed, there is no credible evidence supporting the theory that the first officer deliberately dove the aircraft toward the ocean. To the contrary, there is overwhelming evidence refuting it.

3.B. The First Officer Did Not Deliberately Act to Cause this Crash The factual record developed in the investigation conclusively refutes the initial deliberate act theory widely reported in the early days following the accident. indeed, no credible facts have been produced to support this theory. The following sections discuss the evidence refuting the theory.

(I) The First Officer's statement was not "Prayer" and Does Not Support a Theory Based on the Deliberate

Act The deliberate act theory was based, in large part, on the initial inaccurate translation of an statement repeated several times by the first officer.

This phrase was incorrectly translated as, "I place my feet in the hands of God." Once knowledgeable interpreters were brought into the investigation to listen to the CVR recording, the phrase was properly translated as, "I rely on God," a common, every day, Muslim statement used by Egyptian Muslhns and Christians throughout their day-to-day activities, and, particularly, when they are seeking Gods support. It would not be used in conjunction with a suicidal or criminal act.

The CVR crew chairman's report reflects the accurate translation of the first officer's utterance. Religious authorities consulted also support this view.

(See the CVR Group Chairman's report.) consequently the linchpin of the deliberate act theory has been eliminated not only by credible evidence and analysis but also by accurate translation of the CVR.

(2) The First Omcer had no Motive to Kill Himself or Others Aboard Flight 990 The first officer's personal and professional life have been intensely investigated and scrutinized not only by the NTSB, but also by the FBI. No one has identified any motive for the first officer to kill himself and 216 other passengers and crew.

No behavior before the flight has been identified that could in anyway be linked to a suicidal effort. Indeed, friends who new thc first officer a',tl saw him dr ri' g tl c days bclorc tl c ` ccidcut reportctl that he was acting as he always did.

The first officer had no over riding personal, professional, medical or financial problems. To the contrary, he and his family where respected in his community.

He was also looking forward to his son's up coming wedding. And, although his daughter was being treated for lupus in Los Angeles ,he was financially capable of paying for the relatively expensive treatment.

Additionally, the first officer's medical history is completely devoid of any reference to a diagnosis or treatment for any mental health problems, including depression. And finally, no psychiatrist or psychologist has providea any analysis supporting the deliberate dive the airplane in the ocean.

Other facts inconsistent with that of a person contemplating deliberate action include the fact that he was Bringing back to Egypt for his family and that the day before the flight, he offered viagra to another EgyptAir pilot, but kept several for his own future use.

(3) The First Omcer Did Not Use His Seniority to Insist that He be Allowed to Fly the Airplane It has been erroneously reported in the media that the first officer used his seniority to take over the first officer flying duties so that he could position himself at the controls. Even a cursory review of the CVR transcript does not support this allegation.

EgyptAir did not have a formal policy regarding crewmember relief. A relief crewmember could be asked to fly at any time during a flight. In this instance, Gameel el Batouty discussed the fact that he could not sleep and offered to fly earlier then his scheduled rotation. The flying first officer agreed.

From the onset of this investigation, the FBI has been very closely involved in all the facts surrounding it. At no time, did this agency attempt to take the lead as would be the case if there were suspicion of criminal behavior.

(4) Data Collected From the CVR and FDR Does Not Support the "Deliberate Act" Theory.

The following additional facts from the CVR and FDR also refuted the deliberate act theory:

(a) The CVR report raises the distinct possibility that the first officer was not alone in the cockpit at the onset of the dive. Four voices where identified on the CVR before the dive began and before the captain left the cockpit.

Indeed, after the captain left the cockpit the cockpit door was not closed, and other crewmembers were probably resent or in close proximity to the cockpit.

b. The captain returned to the cockpit ahnost immediately after the dive started.

There is no indication on the CVR of a struggle or disagreement between the first officer, the captain or anyone else. There was also no effort to incapacitate the first officer or to restrain him.

C. The cockpit conversations showed an effort at teamwork rather than a crew working at cross-purposes.

d. Only 6 degrees of elevator movement occurred during the dive, even though 15 degrees of elevator authority was available at the beginning of the dive. Further, it was calculated that at the beginning of the dive the first officer's control column moved 3.5 degrees when about I I degrees of movement was available.

Had the first officer wanted to deliberately dive the airplane in the ocean, he would probably have used more down elevator to cause a steeper dive.

e. The thrust levers were reduced during the early stages of the dive. Such a control input is inconsistent with an attempt to deliberately dive the airplane in the ocean. To the contrary, it is compelling evidence of an effort to slow the descent.

f. The flight crew maintained an essentially wings-level attitude and a consistent heading during the dive. The flight crew also corrected for bank angle when the aircraft began to roll. This controlled flight profile is not consistent with more radical maneuvers that would probably be used if deliberate actions were being attempted.

g. The FDR and CVR correlation shows that soon after the dive started, the captain asked, "What is happening?" he asked this question again as the airplane was recovering. If the first officer were attempting a deliberate dive for the airplane in the ocean, the captain would not have asked this question as the aircraft was recovering from an 1 8.000-foot dive.

h. Commands, made subsequent to the "what is happening" questions also addressed the crew's attempts to control the airplane and did not question the first officer's behavior, like saying for example "what are you doing"- "stop what you are doing"

i. The crew's shutting off the fuel control levers may have been a response to a potential engine flameout. The FDR recorded a warning after a low oil pressure condition. If the crew concluded a dual engine flame-out had occurred as a result of this condition and as result of the attitude of the airplane, they would have initiated the relight procedure which starts with moving both fuel levers to the off position.

j. A command was given a short thne later by the Captain to "shut the engines". This order was confinned by the statement, "It's shut." This shows a crew working together.

k. Analysis shows that the flight crew recovered the aircraft from the dive. This also indicates that the crew working together to control the aircraft.

(5) Simulator Testing Suggests That At Least Three Crew Members Were In The Cockpit During The Dive

Simulations at Boeing suggest that the captain and the first officer were not alone in the cockpit during the dive. The presence of others is indicated by the fact that if either the captain or first officer had let go of their control columns to shut the engines or to deploy the speedbrake (as shown on the FDR), the aircraft would have pitched down at the same time. No such change in pitch was recorded on the FDR.

(6) The Split Elevators Do Not Support The Conclusion That There Was A Struggle In The Cockpit But Could Be Easily Attributed To Cable Break.

The deliberate act theory has also been based on the FDR's recording of a split between the right and left elevators which, according to the theorists, indicated the captain's attempt to wrest control of the airplane from the first of ficer.

After detailed analysis of the FDR and the CVR, this conclusion is seriously flawed for at least three reasons.

First, the CVR provides no indication of a struggle, argument, or refusal to follow a command. Surely, there would have been at least some noise words recorded by the CVR had there been any hint the first officer was acting improperly, much less trying to kill everyone on board the aircraft.

Second the FDR does not record the position of the control column at either the captain's or the first officer's station.

Accordingly, one cannot conclude from examining only the FDR data that pilot input to his control column caused the elevators to be in a given position.

Instead, elevator position is recorded by instrumentations located at the elevator hinges and could be due to pilot input, mechanical malfunction in the elevator control system, aerodynamic forces acting upon the elevator surfaces, or any combination of these. For instance, if the right elevator was being commanded by malfunctioning

actuators to nose the aircraft down, the captain could, after pulling on his control column with sufficient force, cause the left elevator control to split from the right elevator and move to a position to cause the airplane to climb (as this aircraft ulthnately did).

The cause of the control movements in this example could not be explained by simply examining the FDR data alone, although the FDR data would be completely consistent with this possible scenario.

Third, at the same moment the elevators split, At ahnost the same time, the inboard and the outboard ailerons showed behavior that was not consistent with the Boeing 767 aileron system design. Further, when this unusual aileron movement occurred during the dive, the aircraft's speed was approaching Mach 1.0, which is much higher than the maximum aircraft operating speed.

It's likely, however, that aerodynamic shocks were occurring at the control surfaces, and this may have caused the unusual aileron movement. Knowing why the ailerons moved so unusually at the same time as the elevator split accurate explanation for the unusual elevatomnovement.

Fourth, the ground test results concerning malfunctions of one of the elevator body cable (combinations of break and jam conditions at different ends), show several elevator split conditions when swapping at the elevator control columns from the control cabin.

However, the Egyptian Civil Aviation Investigation Team asked to fully conduct the same ground tests for the case of "aft cable break, forward cable jam" to investigate in full this scenario.

3.C Conclusion the first officer did not intentionally dive the aircraft into the ocean

4. The first officer may have disengaged the autopilot to address an operational concern

It is clear from the FDR that the autopilot was disengaged several seconds before the dive began. There is, however, no direct evidence from either the CVR or the FDR to explain why the autopilot was disengaged.

There is some evidence to indicate that the first officer may have been addressing an optional concern, such as abnonnal elevator behavior, as previously experienced on the same aircraft during approach in Lax - Los Angeles.

The possibility remains, however, that the pilot intentionally maneuvered the airplane to avoid a collision or to respond to some other emergency. No substantial evidence supporting or negating such a possibility has been uncovered.

The most significant evidence on this issue -the radar data -- is inconclusive because the Relevant Authority will not release infonnation necessary to analyze thoroughly the potential, and as yet, unidentified radar targets.

Conclusion

At this point in the investigation considering the factual evidence gathered, it is clear that the first officer did not deliberately dive the airplane in the ocean. Further investigation of the elevator control system's design in conjunction with the other factual information available is necessary before a conclusion can be reached regarding the true cause of this accident.

Moreover, The investigation should include tests to assist in more complete and precise analysis, including more detailed tests for the failure condition "Aft elevator cable break with fwd end of broken cable jammed", taking into account the dynamic loads on the elevator surfaces, use of more consistent elevator feel pressures.

In addition, further investigation for radar data and sound spectrum analysis are also necessary to completely rule out the possibility of conflicting traffic or cockpit intrusion. Until this work is accomplished, the cause of this accident cannot be truly established.

In the ECAA's view, when 217 lives are lost in an airplane accident, it is not acceptable to undertake anything less than a thorough, complete and objective investigation. It is not acceptable to ignore legitimate investigative steps because of a " belief " that they will yield little additional information.

It is not acceptable to assert a conclusion as to probable cause based on the supposed absence of evidence of mechanical failure. The families of the Flight 990 victims and the international aviation community deserve more; they deserve candor, objectivity and honesty. What caused the crash of EgyptAir Flight 990? The fact is, on the complete record of this case, we do not know.

Chief of the Egyptian investigation Team

Capt. Mohsen El Missiry

Flight 990 crash

Previous Stories:
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  Egyptian American sides study findings of tests on Boeing 767 plane tests   (9/8/2001)
  Rayan, Boeing Chairman meet on EgyptAir crash   (7/30/2001)

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